Due to rapid advance in the electronic manufacture technology, a breakthrough in the light-production effect of the LED helps to improve the display ability of the LCD screens. Technically speaking, the LED has presently reached the extent of serving half the ability of cold cathode tube. It is hoped that by the year 2005, the light-production effect of the LED may exceed than that of the cold cathode tube. Due to swift response and since the LED can emit visible light, such as red, blue and green, the high cost color filters presently used in the LCD screen are likely replaced by the LEDs in the near future so as to provide wonderful images and sufficient brightness to the LCD screen. In view of lesser power consumption but providing higher lighting efficiency and longer service life, the role of the LED in the LCD device production is considerably prospective. Once the light-production effect of the LED is equal to or exceeds that of the cold cathode tube, the use of LED in the electronic devices will become much important. Presently, LEDs has been successfully used in traffic lights due to their ability in producing red and green colors. If the light-production effect of the LED can be elevated to a certain extent, the possibility of the LED to totally replace current light emitting lamps would be feasible. Also, it is well known that the LED is superior to the conventional light emitting in lower power consuming and low heat generation.
Referring to FIG. 1, a partially fragmentary view of a conventional LED module 10 is shown to include a housing 12, a circuit board 13, an LED 14, a light reflective plate 16 and a light diffusing plate 18. The conventional LED module 10 can be used in the light emitting lamp or a traffic light. It can also serve as the backlight light module of an LCD device. In the conventional LED module, the circuit board 13 is electrically connected to the LED so as to control the activation of the latter. In other electronic device, the circuit board 13 is used to control the display of the LCD device that is mounted above the conventional LED module.
As illustrated in FIG. 1, the LED 14 has a mounting portion 143 mounted on the circuit board 13, and a light-emitting portion 141. In another conventional LED module, the LED can be directly mounted on a base plate of the housing 12 (not shown).
The light reflective plate 16 can reflected the light beams emitted from the light-emitting portion 141 of the LED 14 upward, thereby effectively employing the light beams thereof. The outer periphery of the light reflective plate 16 is mounted on the housing 12 above the base plate, and has an LED hole exposing the light-emitting portion 141 above the reflective plate 16 while the mounting portion 143 of the LED is disposed below the reflective plate 16. In some prior technique, the mounting portion 143 of the LED 14 is used for supporting the reflective plate 16 thereabove.
The outer periphery of the light diffusing plate 18 is mounted on the housing 12 above the reflective plate 16 so that the diffusing plate 18 can diffuse the light beams reflected by the reflective plate 16, thereby causing several light reflection actions between the diffusing and the reflective plates 18, 16, which, in turn, provides incredible brightness of the LED 14.
FIG. 2 illustrates a partially fragmentary view of another conventional LED module 20 which includes an LED 14 that emits light beams in sidewise manner such that majority of the light beams will not reflect upward. Unlike to the previous conventional LED module 10, the conventional LED module 20 shown in FIG. 2 has an auxiliary diffusing plate 22 disposed in the housing 12 between the reflective plate 16 and the diffusing plate 18 more closer to the former such that the auxiliary diffusing plate 22 provides wider angle of light reflection by virtue of wider angle of incidence when the light beams emitted by the LED hit the auxiliary diffusing plate 22. The wider angle of reflection enhances the upward scattering light beams, thereby reflecting the entire portion of the light beams in order to provide effective brightness of the LED. Due to aforesaid reasons, the conventional LED module of FIG. 2 provides a better color mixing effect. Under the present condition, it is desired to select the LED module of FIG. 2 for use in the display of the LCD system so as to provide uniform brightness throughout the entire length of the display.
Presently, the LED module is used only in the small-sized LCD device, such as handheld PDA with LCD screen. The researchers in the LCD manufacturing world are eager to solve the possible difficulties once the LED modules are employed in the large-sized LCD device since the larger or wider LCD screen requires a larger LED module as its backlight module. As illustrated in FIGS. 1 and 2, increase in the dimension of the LED module consequently requires a larger number of LEDs therein. In other words, the sizes of the reflective plate 16, the diffusing plate 18, and the auxiliary diffusing plate 22 must also be increased, thereby causing the middle portion of these plates to bend downward by virtue of gravity. The housing 12 has to burden a relatively large amount of weight and subsequently weakening the rigidity of the housing 12. In addition, the downward bending of these plates is aggravated since the reflective plate 16 is generally made from metal. (Aluminum) and the diffusing plates 18, 22 are made from glass or acrylic materials which are susceptible to bend. The downward bending of these plates within the LED module can result in uneven scattering of light beams in the LED module, hence degrading the display ability of the LCD device.